09-15-2013, 07:21 AM
Last winter I decided to start a project to convert a surplus Cushman 3 jaw chuck to a "soft jaw" chuck for my 12 x 36 lathe.
The chuck didn't have the necessary 2 piece jaws so I wondered if they might be available.
Cushman didn't reply to my query for jaw possibilities so I thought about machining the existing ones.
The jaws laughed at my file hardness test. The file lay trembling in the file drawer.
So, with the recommendation of a buddy (on another forum) I put the jaws in the coals of my then constantly burning airtight stove.
Removed them to the constantly at hand ash can.
20+/- hrs. later the next day, after cooling slowly the file had it's revenge.
The jaws were soft enough to cut with my homemade bandsaw.
[attachment=6549]
Next was the drill test to see if they could be drilled and tapped.
[attachment=6550]
And now on to step 3 to machine the new, low tops on the jaws.
[attachment=6551] [attachment=6552]
Here's the project now stalled, awaiting a threaded backplate for the lathe and finally soft jaws.
[attachment=6553]
There has been some talk about re-hardening the jaw bases but I think I'll leave them as they are because I suspect they will get relatively infrequent use.
Back plate progress will be reported when and if it happens.
The chuck didn't have the necessary 2 piece jaws so I wondered if they might be available.
Cushman didn't reply to my query for jaw possibilities so I thought about machining the existing ones.
The jaws laughed at my file hardness test. The file lay trembling in the file drawer.
So, with the recommendation of a buddy (on another forum) I put the jaws in the coals of my then constantly burning airtight stove.
Removed them to the constantly at hand ash can.
20+/- hrs. later the next day, after cooling slowly the file had it's revenge.
The jaws were soft enough to cut with my homemade bandsaw.
[attachment=6549]
Next was the drill test to see if they could be drilled and tapped.
[attachment=6550]
And now on to step 3 to machine the new, low tops on the jaws.
[attachment=6551] [attachment=6552]
Here's the project now stalled, awaiting a threaded backplate for the lathe and finally soft jaws.
[attachment=6553]
There has been some talk about re-hardening the jaw bases but I think I'll leave them as they are because I suspect they will get relatively infrequent use.
Back plate progress will be reported when and if it happens.